1. Field of the Invention
The present invention relates to a laser gyro and an electronic device using the same.
2. Related Background Art
Conventionally, optical gyros that use a semiconductor laser device provided with a ring-shaped active layer have been proposed (for example, JP2000-230831 A). Since a difference in frequency is generated (the Sagnac effect) between two laser lights that circulate in the opposite directions to each other in a ring-shaped active layer when a gyro rotates, rotation of the gyro can be detected by detecting the difference. The difference in frequency Δf between the two laser lights is expressed by the following Formula:
      Δ    ⁢                  ⁢    f    =                    4        ⁢        A                    λ        ⁢                                  ⁢        nL              ⁢    Ω  
In the Formula, L denotes the circulation length of an optical path, A denotes the inner area of the optical path, λ denotes the wavelength of the laser light, n denotes the refractive index of the optical path and Ω denotes angular velocity.
Sensitivity of the gyro can be enhanced by increasing the difference in frequency between the two laser lights. As one of such measures, a measure is known which increases the A/L value by enlarging the size of the ring-shaped optical path.
However, enlarging the size of the ring-shaped optical path causes a problem in the semiconductor laser device where the threshold current becomes high and the power consumption increases.